2. We have two aqueous solutions: (1) starch dissolved in water, and (2) Iodine dissolved in water. The iodine solution is sealed inside a bag made of dialysis tubing, which is floating in a beaker filled with the starch solution (see diagram below). Starch is not able to cross the material that makes up the dialysis tubing, but both water and iodine can pass freely through the tubing. What will happen in each case? Explain your choices. (Your answer should clearly explain which substances move across the tubing (if any), what direction they move, by what method of membrane transport they move, and why they would move by that method.) (4 points)
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This movement occurs through the process of diffusion, as iodine moves from an area of higher concentration (inside the tubing) to an area of lower concentration (in the beaker). Show more…
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Use the illustrations of a different experiment shown below to answer the questions that follow: Note that the dialysis bag is selectively permeable to water and iodine (IKI), but not to starch. Bag H2O Beaker Water & IKI solution Selectively permeable dialysis bag Closer look Water and starch solution Selectively permeable membrane Starch 1. The net movement of iodine molecules is (pick one: into the bag; into the beaker; in both directions; in neither direction). 2. The net movement of starch is (pick one: into the bag; into the beaker; in both directions; in neither direction). 3. The net movement of water is (pick one: into the bag; into the beaker; in both directions; in neither direction).
Sri K.
1. Define diffusion. 2. A glucose-starch solution was placed in dialysis tubing. Then, the tubing was placed in a cup containing IKI indicator. Did starch stay within the tubing or move out of the tubing? Did IKI indicator stay in the solution in the cup or move into the tubing? Support your answer with the observations. 3. Put the IKI solution in the cup and the contents of the dialysis tubing were tested with the glucose test strips. Did glucose stay within the dialysis tubing or move out of the tubing? Support your answer with the observations. 4. How is a cell membrane similar to the dialysis tubing used? 5. Might it be inferred that: a) starch and glucose molecules are the same size, b) starch molecules are larger than glucose molecules, or c) starch molecules are smaller than glucose molecules. Explain your answer. 6. How did hypotheses compare with outcomes? 7. What is osmosis? 8. Is osmosis a form of active or passive diffusion/transport? Why? 9. Why do intravenous (IV) solutions need to have the same tonicity as blood? 10. What occurred when blood mixed with solution? Why did this occur? 11. Is the movement of substances in this exercise active or passive?
Madhur L.
Kidney Dialysis Semipermeable membranes of the sort used in kidney dialysis do not allow large molecules and cells to pass but do allow small ions and water to pass. Figure $P 11.7$ shows such a membrane separating fluids of various compositions. a. In which direction does the water flow in each apparatus? b. In which direction do sodium ions Aow in each apparatus? c. In which direction do the potassium ions flow in each apparatus?
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